Apparatus for testing boat fenders



March 18, 1969 D. L. DEAN APPARATUS FOR TESTING BOAT FENDERS Filed March28, 1967 Illllll INVENTOR.

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FEOM azyie 3,433,050 APPARATUS FOR TESTING BOAT FENDERS Duff L. Dean,North Hollywood, Calif., assignor, by mesne assignments, to Triple DIndustries, Inc., Burbank, Calif., a corporation of California FiledMar. 28, 1967, Ser. No. 626,546 US. Cl. 7311 10 Claims Int. Cl. Gtllm17/04 ABSTRACT OF THE DISCLOSURE A vehicle and means, such as rails forguiding the vehicle along a straight path. The vehicle is transportedback and forth between the ends of the path. The vehicle has aretractable mechanism for exerting an adjustable downward force as thevehicle moves. During test of radial strength, a boat fender is locatedunder the lowered force-exerting mechanism, thereby rolling back andforth with the vehicle, while being subjected to a deforming force.

Background of the invention This invention relates to boat fenders and,more particularly, to apparatus for testing the strength characteristicsof boat fenders.

For many years cocoa and rope mats, pieces of cork, and solid nonporousrubber have served as boat fenders. These structures have proved usefulto reduce or eliminate damage upon collision of two boats or a boat witha dock by absorbing the impact in part and distributing it over a largerarea, but they suffer from numerous shortcomings. For the most part,these fenders absorb water, and nonbuoyant and subject to fast wear, andlack the ruggedness and resilience to withstand for extended periods oftime the tremendous impacts that are encountered in normal use.

Recently a boat fender structure has been developed that overcomes theseshortcomings to a large extent. This structure comprises a hollow,rubber core around which sheets of buoyant resilient material are woundin the form of a spiral and cemented together, The resulting cylindricalbody is bagged, so to speak, in a snug-fitting, watertight cover.Fixtures mounted at either end of the structure are connected by a steelcable running through the hollow interior of the core. In use, thesefenders are draped over the hull of the boat by lines secured to thefixtures. This fender structure has found wide acceptance because it iswatertight, buoyant, rugged, and resilient. In addition, it isfire-resistant and easy to clean and repair.

Purchasers of the cylindrical boat fenders, notably the United StatesNavy, have prescribed certain procedures for testing the strengthcharacteristics of a few samples from each lot of boat fendersmanufactured. The selected samples must be able to withstand a minimumdownward force exerted on its cylindrical surface as the fender rollsalong the ground or other surface without splitting open. As the fenderrolls, the downward force deforms it in a continually changing radialplane thereof. After this test, the axial strength of the fender istested by pulling one of. the fixtures. In order to pass the lattertest, the fender must be able to withstand a minimum axial force withouthaving the fixture pull loose.

Summary of the invention According to the invention, a vehicle isprovided that is restrained to move along a substantially straight path.Most advantageously, the vehicle rides on rails. The vehicle istransported continuously back and forth between the ends of the path.The vehicle has a retractable mechanism for exerting an adjustabledownward force as it nitcd States Patent moves back and forth, Duringtest of the radial strength, the boat fender is located under thelowered force-exerting mechanism and rolls along the ground or othersurface as the vehicle moves back and forth. To test the axial strengthof the fender, the vehicle is simply stopped and the fender is retainedby the lowered mechanism while the fixture is pulled.

Brief description of the drawing The features of a specific embodimentof the invention are illustrated in the drawing, in which:

FIG. 1 is a side elevation view of apparatus for testing boat fenders;and

FIG. 2 is a front elevation view of the apparatus of FIG. 1.

Descrpition of a specific embodiment In the drawing, a vehicle 1 rideson parallel rails 2a and 2b that serve to guide vehicle 1 along astraight path. Vehicle 1 has wheels 4a and 5a in engagement with rail 2aand wheels 4b and 5b in engagement with rail 2b. Wheels 40, 4b, 5a, and5b are rotatably supported by yokes 6a, 6b, 7a, and 7b, respectively, onwhich vertical support members 8a, 8b, 9a, and 9b, respectively, rest,Arms 10 and 11 extend horizontally from the top of vertical supportmembers 8a and 9a, respectively. As explained in detail below, arms 10and 11 actuate switches that control the movement of vehicle 1 on rails2a and 2b. Horizontal support members 12a and 13a run along the lengthof vehicle 1 between vertical support members 8a and 9a, whilehorizontal support members 12b and 1312 run along the length of vehicle1 between vertical support members 8b and 9b. Similarly, horizontalmembers 14 and 15 run along the width of vehicle 1 between verticalmembers 8a and 8b, and horizontalsupport members 16 and 17 run along thewidth of vehicle 1 between vertical support members 9a and 9b.

A horizontal platform 20 is located between vertical support members 8a,8b, 9a, and 9b, The vertically oriented, movable arms of air cylinders21a, 21b, 22a, and 22b are attached to platform 20 at its four corners.Air cylinders 21a and 21b are attached to horizontal support member 14by brackets 23a and 23b, respectively. Similarly, air cylinders 22a and22b are attached to horizontal support member 16 by brackets 24a and24b, respectively. A heavy body 25, which could, for example, comprise apile of bricks, rests on platform 20. Body 25 weighs more than thedownward force to be exerted on the boat fender under test. At its ends,platform 20 has extensions 26a, 26b, 27a, and 27b, which are parallel tohorizontal support members 15 and 17. Two cylindrical guides, such asthose designated 28 and 29 in FIG. 1, are attached to each end ofplatform 20 with their axes parallel to horizontal support members 12and 13. These guides glide along the respective vertical support members(8a, 8b, 9a, and 9b) as platform 20 is raised and lowered, therebyserving with extensions 26a, 26b, 27a, and 27b to prevent lateral motionof platform 20.

Before a boat fender is to be tested, platform 20 is first raised orretracted by actuating air cylinders 21a, 21b, 22a, and 22b. Then a boatfender, designated 35 in the drawing, is placed under platform 20, whichis then lowered by releasing air cylinders 21a, 21b, 22a, and 22b, untilboat fender 35 becomes deformed. The limit on the downward excursion ofplatform 20, and therefore the fraction of the weight of body 25actually exerted on fender 35, is controlled by threaded stops such asthose designated 36 and 37 in FIG. 1. These stops extend verticallythrough threaded holes in wheel yokes 6a, 6b, 7a, and 7b. When platform20 is lowered, it moves downward until it comes to rest on the threadedstops, which are vertically adjustable by screwing them in or out.

A beam 38, which is at least as long as the path along which vehicle 1travels, is attached on the side of vehicle 1 to vertical supportmembers 8a and 9a. A roller chain 39 is attached to the ends of beam 38and extends along the length thereof. A sprocket 40, which is mounted onthe drive shaft of a reversible electric motor 41, engages roller chain39. A switch is located at either end of the path of vehicle 1. Eachtime one of the switches is actuated, the direction of rotation ofsprocket 40 changes. One of the switches, designated 42 in FIG. 1, isactuated when a member 43, which is pivotable about a horizontal axis,is tripped by arm 11. Switch 42 is connected to motor 41 by a pair ofleads 44. Similarly, the other switch which is not represented in thedrawing is actuated by a pivotable member which is tripped by arm 10 asvehicle 1 reaches the other end of its path of travel. The other switchis connected to motor 41 by a pair of leads 45.

After platform is lowered onto boat fender 35, motor 41 is energized. Asvehicle 1 reaches the end of the path of travel, the correspondingswitch is actuated and motor 41 is reversed. Thus, vehicle 1 travels tothe other end of its path, at which point, the corresponding switch isactuated to reverse motor 41 once again. Vehicle 1 continues to rideback and forth on rails 2a and 2!) between the two ends of the pathuntil motor 41 is deener- .gized. During this time, boat fender 35 rollsalong the ground under platform 20. As boat fender 35 rolls, the radiusof the cylinder, along which the downward force is exerted, continuallychanges and with it the direction of deformation of boat fender 35 alsochanges.

After the radial strength of the boat fender is tested and motor 41 isdeenergized, fender 35 remains under platform 20 while its axialstrength is tested by pulling on one of the fixtures.

What is claimed is:

1. Apparatus for testing the strength of boat fenders comprising: avehicle; means for restraining the vehicle to move along a substantiallystraight path; means for transporting the vehicle back and forth betweentwo points on the straight path; and means on the vehicle for exerting adownward force on a boat fender resting on the surface along which thevehicle moves while the vehicle is being transported, the force beamapplied to compress the fender while the vehicle moves back and forth soas to stress the fender while it is rolling and to simulate the forcesin actual use of the fender.

2. The apparatus of claim 1, in which the restraining means are railsand the vehicle has wheels that engage the rails.

3. The apparatus of claim 1, in which the means for exerting a downwardforce is retractable out of contact with a boat fender resting on thesurface along which the vehicle moves.

4. The apparatus of claim 1, in which the means for exerting a downwardforce is a horizontal platform.

5. The apparatus of claim 4, in which the horizontal platform isattached to the movable arms of cylinders which are fixed with respectto the vehicle such that the platform is retractable away from thesurface along which the vehicle moves. v

6. The apparatus of claim 1, in which the means for exerting a downwardforce exerts an adjustable downward force on a fender resting on thesurface.

7. The apparatus of claim 5, in which adjustable stops are provided tolimit the downward movement of the platform, thereby controlling theamount of force applied to the fender.

8. The apparatus of claim 1, in which the vehicle has vertical supportmembers and the platform has guide means for maintaining its lateralposition relative to the vertical support members.

9. The apparatus of claim 1, in which the means for moving the vehicleback and forth comprises a reversible motor that is controlled byswitches located at either end of the path of the vehicle, the switchesbeing actuated by means located on the vehicle as the vehicle approachesthe end of the path.

10. The apparatus of claim 9, in which a roller chain is mounted to thevehicle and extends along its length a distance at least as long as thepath of travel of the vehicle and a sprocket driven by the motor engagesthe roller chain.

References Cited UNITED STATES PATENTS 2,113,290 4/1938 Benjamin 7373,041,868 7/1962 Schaschl et a1 73-7 X 3,262,310 7/1966 Gr-uich et al.73-94 RICHARD C. QUEISSER, Primary Examiner.

J. WHALEN, Assistant Examiner.

US. Cl. X.R. 73--94; 323-4

